Synthesis and properties of p-C8-bridged hydroquinones and p-benzoquinones

The cycloaddition of the dispiro compound, $\text{2}$, with a variety of 1,3-butadienes affords diacetates of $\text{p}$-C₈-bridged hydroquinones, which are led to the corresponding hydroquinones and $\text{p}$-benzoquinones.     

The ipso-nitration of p-cresol

The nitration of $\text{p}$-cresol by nitric acid in aqueous sulphuric acid involves ~40% $\text{ipso}$-substitution at C^Me. The 4-methyl-4-nitrocyclohexa-2,5-dien-1-one (I) formed undergoes an acid-catalysed rearrangement to 4-methyl-2-nitrophenol.     

Stereoselective photosolvolyses of ipso-acetoxynitro-adducts of p-xylene

Diastereoisomers of 1,4-dimethyl-4-nitro-2,5-cyclohexadienyl acetate exchanged acetoxyls for alkoxyls on irradiation in alcohols to give the diastereoisomers of alkyl, 1,4-dimethyl-4-nitro-2,5-cyclohexadienyl ethers in isomer ratios of 70:30, whereas the irradiation in pentane yielded $\text{p}$-xylene.     

Solvolytic behavior of p-dimethylamino-α-bromostyrene in water solutions

Nmr and UV studies show that $\text{p}$-dimethylamino-$\text{α}$-bromostyrene, I, undergoes S_Nl reaction in H₂O and HClO₄ (^kS_Nl = 6 × 10^?1sec.^?1 at 25°). The vinyl cation has an extraordinary selectivity for capture by aromatic amines relative to H₂O, including I itself to give the dimer II.     

Behavior of p-dimethylamino-α-bormostyrene and its dimer in dioxane-water

Monomeric $\text{p}$-dimethylamino-$\text{α}$-bromostyrene undergoes S_Nl increasingly slowly in 60 to 91% dioxane. Reaction is catalyzed by HClO₄, NaOH and NaClO₄. Dimer 11 reverts to monomer I in 91% dioxane. There is only a small solvent effect on the solvolysis rate of II.     

Decomposition of arilazides and p-tosylazide by thf/n-botyllithium. A new source of diazomethmne

Variously substituted arylazides, as well as $\text{p}$-tosylazide, when allowed to react at room temperature with THF previously treated with $\text{n}$-butyllithium, undergo a rapid decomposition affording the corresponding amines and fomamides, together with diazomethane. This diazo transfer (with deformylation) reaction is thought to involve the enolate of the acetaldehyde generated by the known cycloreversion of THF in the presence on $\text{n}$     

Activation of methylenetriphenylphosphorane by reaction with t-butyl- or sec-butyllithium

Experimental details are provided to support a previous report that α-methylenetriphenylphosphorane ($\text{1}$) may be activated for reaction with unreactive substrates such as epoxides and hindered ketones by α-metallation to $\text{2}$.     

Stereocontrolled (E,Z and erythro, threo) synthesis of ⊙-hydroxyallylic sulphides

All four isomers of substituted 3-alkylthio-4-hydroxybutenes have been synthesised: both the geometry of the double bond and the relative stereochemistry of the two chiral centres are controlled.     

Olefin metathesis in polycyclic frames 1. A new way to cis, syn, cis - tricyclopentanoids (acs-C11-triquinanes)

A novel olefin metathesis sequence permits ready access to functionalised $\text{cis}$, $\text{syn}$, $\text{cis}$-tricyclo [6.3.0.0^2,6] undecane based bis-enones. These bis-enones have been shown to undergo cage cyclisation in sunlight with remarkable ease and efficiency.     

Advanced sedex (sensitive detector of exothermic processes)

The instrument described is suitable for the investigation of the thermal behaviour of substances and reaction mixtures under production conformable conditions; this is made possible by the sophisticated design of the sample chamber: easy stirring of the samples, measuring under any gas atmosphere and while bubbling gas through the sample, choice of the sample container and visual observation during the measurement. The control device allows the choice of one of three operational modes: constant temperature, linear increase in temperature, and adiabatic control; this permits the application of the SEDEX apparatus for a variety of methods including dynamic scanning, isoperibolic measurements, and (quasi) adiabatic studies.     

Facile synthesis of p-chloromethylated styrene by elimination reaction of p-(2-bromoethyl)benzylchloride using potassium hydroxide as a base under phase transfer catalysis

Phase transfer catalyzed elimination reactions of $\text{p}$-(2-bromoethyl)-benzylchloride with potassium hydroxide gave $\text{p}$-chloromethylated styrene in high yield.     

Pyridinium p-toluenesulfonylmethylide as a formyl anion equivalent

Pyridinium $\text{p}$-toluenesulfonylmethylide serves as a formyl anion equivalent and, in the presence of an alcohol, undergoes 1,4-addition to $\text{N}$-substituted maleimides to give alkoxy- (or aryloxy)-methylene-succinimides. The protected aldehyde group can be liberated readily.